title: Stable isotope tracer to determine uptake and efflux dynamics of ZnO Nano- and bulk particles and dissolved Zn to an estuarine snail.
abstract: Zinc oxide nanoparticles (ZnO NPs) are among the most commercialized engineered nanomaterials. Their biological impact in aquatic organisms has been associated with dissolution, but there is also evidence of nanospecific effects. In this study the waterborne uptake and efflux kinetics of isotopically labeled (68)ZnO NPs (7.8 ± 1.2 nm), in comparison to aqueous (68)Zn and (68)ZnO bulk particles (up to 2 μm), were determined for the estuarine snail Peringia ulvae following a 7 d exposure (nominally 20 μg (68)Zn L(-1)) and 28 d depuration. Detection of the (68)Zn label was achieved by high precision multiple-collector ICP-MS (MC-ICP-MS). Previous characterization in artificial estuarine water revealed that the NPs underwent initial aggregation and solubilized up to 60% within 1-2 days. Bulk and aqueous forms were significantly more bioavailable than (68)ZnO NPs (p < 0.05), but after correcting for dissolution, aqueous (0.074 L(-1) g(-1) d(-1)) and NP (0.070 L(-1) g(-1) d(-1)) uptake rate constants were highly comparable. The rate constant of loss for (68)Zn aqueous (0.012 ± 0.005 d(-1)) and (68)ZnO NPs (0.012 ± 0.007 d(-1)) were identical. These results strongly suggest that in this exposure scenario the bioaccumulation of Zn from ZnO NPs is primarily dependent upon solubility.
authors.affiliation: Life Sciences, Natural History Museum , Cromwell Road, London SW7 5BD, England. f.khan@hw.ac.uk
authors.forename: Farhan R
authors.initials: FR
authors.lastname: Khan
authors.forename: Adam
authors.initials: A
authors.lastname: Laycock
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Dybowska
authors.forename: Fiona
authors.initials: F
authors.lastname: Larner
authors.forename: Brian D
authors.initials: BD
authors.lastname: Smith
authors.forename: Philip S
authors.initials: PS
authors.lastname: Rainbow
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Luoma
authors.forename: Mark
authors.initials: M
authors.lastname: Rehkämper
authors.forename: Eugenia
authors.initials: E
authors.lastname: Valsami-Jones
mesh_terms: D000818:Animals; D063366:Estuaries; D007554:Isotopes / Q000032:analysis*; D012908:Snails / Q000737:chemistry*; D012995:Solubility; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D007554:Isotopes; D015034:Zinc Oxide